The present invention relates to an actuator for a variable valve operating apparatus or system for varying a valve operating characteristic such as a valve lift or an operation angle of an intake or exhaust valve of an internal combustion engine in accordance with engine operating condition or conditions.
A Japanese patent document JP 2006-144551A discloses an actuator for a variable valve operating apparatus. This variable valve operating apparatus includes a drive shaft driven through a sprocket by a crankshaft of an engine, a cam shaft including at least one swing cam, a multi-link motion transmitting mechanism connected between the drive shaft and the swing cam, a control element such as a control shaft to vary a valve opening/closing timing or timings and an operation angle of an intake valve by varying the posture of the motion transmitting mechanism in accordance with engine operating condition(s), and an actuator to control the rotational angular position of the control shaft.
The actuator includes an electric motor controlled by a control unit, and a speed reducing mechanism for transmitting a rotational force of the motor to the control shaft with speed reduction. The motor includes a motor casing connected with the speed reducing mechanism, motor components such as coil enclosed in the motor casing, and a motor output shaft driven by the motor components. The motor output shaft is received in a shaft insertion hole formed in the motor casing. In the inside circumferential surface of the shaft insertion hole, there is provided an oil seal to prevent leakage of a lubricating oil from the inside of the speed reducing mechanism into the motor casing.